Address information recording apparatus and method, and address information reproducing apparatus and method

ABSTRACT

A method for recording address information to an optical disc ( 5 ) by forming a wobbled groove is provided. The method includes steps S 1  to S 3 . In step S 1 , there is generated address information composed of a sync signal, address data and an error correction code for the address data. In step S 2 , a carrier signal is multiplied by the address information to generate a phase modulation signal. In step S 3 , there is formed on the optical disc ( 5 ) a spiral groove wobbled adaptively to the phase modulation signal.

CROSS-REFERENCE TO RELATED DOCUMENTS

The present patent document is a continuation of U.S. application Ser.No. 10/276,576 filed on Apr. 30, 2003, and in turn claims priority to JP2001-076228 filed on Mar. 16, 2001, and PCT/JP02/02502 filed on Mar. 15,2002, the entire contents of each of which are hereby incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates to an apparatus for, and a method of,recording address information by forming a wobble groove on adisc-shaped recording medium, an apparatus for, a method of, reproducingaddress information from a wobbled groove formed on a disc-shapedrecording medium, a program for recording, and reproducing, addressinformation to, and from, a disc-shaped recording medium, and arecording medium having the program recorded therein.

BACKGROUND ART

Heretofore, a recording medium shaped like a disc such as an opticaldisc, Magnetic disc, magneto-optical disc or the like has a spiralgroove formed thereon for the purpose of tracking. It is already knownto record address information by wobbling the groove adaptively to theaddress information.

Address information to be recorded to a disc-shaped recording medium iscomposed of a sync signal indicative of an address start position and anaddress indicative of address data itself. Some of address informationfurther contain an error correction code (ECC) for the address data.

Since a sync signal included in address signal is not sufficiently long,it cannot have any ECC appended thereto. Unless a sync signal in addressinformation can be reproduced accurately, address data having an ECCappended thereto cannot be reproduced either. In other words, the errorrate of address information depends upon whether a sync signal in theaddress information can be reproduced accurately or not. Therefore, amethod of accurately reproducing a sync signal in address signal shoulddesirably be established.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention has an object to overcome theabove-mentioned drawbacks of the related art by quickly accessing agiven address through accurate reproduction of a sync signal included inaddress information.

The above object can be attained by providing an apparatus for recordingaddress information to a disc-shaped recording medium, the apparatusincluding according to the present invention:

means for generating address information composed of a sync signalincluding a plurality of sync unit patterns, address data and an errorcorrection code for the address data;

a modulating means for generating a phase modulation signalcorresponding to the address information generated by the addressinformation generating means; and

means for forming, on a disc-shaped recording medium, a spiral groovewobbled adaptively to the phase modulation signal generated by themodulating means. The disc-shaped recording medium referred to herein isan optical disc.

In the above recording apparatus, the address information generatingmeans generates address information composed of a sync signal includingfour types of sync unit patterns, address data and an ECC for theaddress data.

Also, the above object can be attained by providing a method forrecording address information to a disc-shaped recording apparatus, themethod including, according to the present invention:

a generating step of generating address information composed of a syncsignal including a plurality of sync unit patterns, address data and anerror correction code for the address data;

a modulation step of generating a phase modulation signal correspondingto the address information generated in the address informationgenerating step; and

a forming step of forming, on a disc-shaped recording medium, a spiralgroove wobbled adaptively to the phase modulation signal generated inthe modulating step.

Also, the above object can be attained by providing a program forrecording address information to a disc-shaped recording medium, theprogram including, according to the present invention:

a generating step of generating address information composed of a syncsignal including a plurality of sync unit patterns, address data and anerror correction code for the address data;

a modulation step of generating a phase modulation signal correspondingto the address information generated in the address informationgenerating step; and

a forming step of forming, on a disc-shaped recording medium, a spiralgroove wobbled adaptively to the phase modulation signal generated inthe modulating step.

Also, the above object can be attained by providing a program forcausing a computer, which controls operations for recording addressinformation to a disc-shaped recording medium, to execute, according tothe present invention:

a generating step of generating address information composed of a syncsignal including a plurality of sync unit patterns, address data and anerror correction code for the address data;

a modulation step of generating a phase modulation signal correspondingto the address information generated in the address informationgenerating step; and

a forming step of forming, on a disc-shaped recording medium, a spiralgroove wobbled adaptively to the phase modulation signal generated inthe modulating step.

Note that this program will also be referred to as “first program” belowfor the convenience of the explanation.

Also, the above object can be attained by providing an apparatus forreproducing an address on a disc-shaped recording medium on the basis ofwobbles of a groove formed on the disc-shaped recording medium, theapparatus including according to the present invention:

radiating means for radiating laser light to the disc-shaped recordingmedium;

return light detecting means for detecting return light from thedisc-shaped recording medium to generate a return light signalcorresponding to the return light thus detected;

wobbling signal generating means for generating a wobbling signalcorresponding to the wobbles of the groove on the basis of the returnlight signal generated by the return light detecting means;

demodulating means for demodulating the wobbling signal generated by thewobbling signal generating means to recover address information composedof a sync signal including a plurality of sync unit patterns, addressdata and an error correction code for the address data;

sync unit pattern detecting means for detecting at least one of theplurality of sync unit patterns included in the sync signal in theaddress information recovered by the address information recoveringmeans;

acquiring means for acquiring the address data and error correction codefor the address data from the address information on the basis of theposition of the sync unit pattern detected by the sync unit patterndetecting means; and

reproducing means for reproducing the address on the basis of theaddress data and the error correction code for the address data,extracted by the acquiring means.

The disc-shaped recording medium referred to herein is an optical disc.

The above address information reproducing apparatus further includesmeans for generating a clock signal on the basis of the position of thesync unit pattern detected by the detecting means.

Also, the above object can be attained by providing a method forreproducing an address on a disc-shaped recording medium on the basis ofwobbles of a groove formed on the disc-shaped recording medium, themethod including, according to the present invention:

a radiating step of radiating laser light to the disc-shaped recordingmedium;

a return light detecting step of detecting return light from thedisc-shaped recording medium to generate a return light signalcorresponding to the return light thus detected;

a wobbling signal generating step of generating a wobbling signalcorresponding to the wobbles of the groove on the basis of the returnlight signal generated in the return light detecting step;

a demodulating step of demodulating the wobbling signal generated in thewobbling signal generating step to recover address information composedof a sync signal including a plurality of sync unit patterns, addressdata and an error correction code for the address data;

a sync unit pattern detecting step of detecting at least one of theplurality of sync unit patterns included in the sync signal in theaddress information recovered in the address information recoveringstep;

an acquiring step of acquiring the address data and error correctioncode for the address data from the address information on the basis ofthe position of the sync unit pattern detected in the sync unit patterndetecting step; and

a reproducing step of reproducing the address on the basis of theaddress data and the error correction code for the address data,extracted in the acquiring step.

Also, the above object can be attained by providing a program forreproducing an address on a disc-shaped recording medium on the basis ofwobbles of a groove formed on the disc-shaped recording medium, theprogram including, according to the present invention:

a radiating step of radiating laser light to the disc-shaped recordingmedium;

a return light detecting step of detecting return light from thedisc-shaped recording medium to generate a return light signalcorresponding to the return light thus detected;

a wobbling signal generating step of generating a wobbling signalcorresponding to the wobbles of the groove on the basis of the returnlight signal generated in the return light detecting step;

a demodulating step of demodulating the wobbling signal generated in thewobbling signal generating step to recover address information composedof a sync signal including a plurality of sync unit patterns, addressdata and an error correction code for the address data;

a sync unit pattern detecting step of detecting at least one of theplurality of sync unit patterns included in the sync signal in theaddress information recovered in the address information recoveringstep;

an acquiring step of acquiring the address data and error correctioncode for the address data from the address information on the basis ofthe position of the sync unit pattern detected in the sync unit patterndetecting step; and

a reproducing step of reproducing the address on the basis of theaddress data and the error correction code for the address data,extracted in the acquiring step.

Also, the above object can be attained by providing a program forcausing a computer, which controls operations for reproducing an addresson a disc-shaped recording medium on the basis of wobbles of a grooveformed on the disc-shaped recording medium, to execute, according to thepresent invention:

a radiating step of radiating laser light to the disc-shaped recordingmedium;

a return light detecting step of detecting return light from thedisc-shaped recording medium to generate a return light signalcorresponding to the return light thus detected;

a wobbling signal generating step of generating a wobbling signalcorresponding to the wobbles of the groove on the basis of the returnlight signal generated in the return light detecting step;

a demodulating step of demodulating the wobbling signal generated in thewobbling signal generating step to recover address information composedof a sync signal including a plurality of sync unit patterns, addressdata and an error correction code for the address data;

a sync unit pattern detecting step of detecting at least one of theplurality of sync unit patterns included in the sync signal in theaddress information recovered in the address information recoveringstep;

an acquiring step of acquiring the address data and error correctioncode for the address data from the address information on the basis ofthe position of the sync unit pattern detected in the sync unit patterndetecting step; and

a reproducing step of reproducing the address on the basis of theaddress data and the error correction code for the address data,extracted in the acquiring step.

Note that this program will also be referred to as “second program”below for the convenience of the explanation.

The disc-shaped recording medium according to the present invention hasformed thereon a spiral groove wobbled adaptively to a phase modulationsignal corresponding to address information composed of a sync signalincluding a plurality of sync unit patterns, address data and an errorcorrection code for the address data. The disc-shaped recording mediumreferred to herein is an optical disc.

In the above address information recording apparatus and method andprogram for recording address information to the disc-shaped recordingmedium, there are generated address information composed of the syncsignal including the plurality of sync unit patterns, address data andan error correction code for the address data, and the phase modulationsignal corresponding to the address information thus generated. Further,the groove wobbled adaptively to the phase modulation signal thusgenerated is formed on the disc-shaped recording medium.

In the address information reproducing apparatus and method and secondprogram, laser light is radiated to the disc-shaped recording medium,return light from the disc-shaped recording medium is detected, thereturn light signal is generated corresponding to the return light, andthe wobbling signal corresponding to the wobbles of the groove isgenerated on the basis of the return light signal thus generated. Thewobbling signal thus generated is demodulated to recover the addressinformation composed of the sync signal including the plurality of syncunit patterns, address data and the error correction code for theaddress data, and at least one of the sync unit patterns included in thesync signal of the address information thus recovered is detected.Further, based on the position of the sync unit pattern thus detected,the address data and error correction code for the address data areextracted from the address information, and an address is reproducedbased on the address data and error correction code for the addressdata, thus extracted.

Also, the above object can be attained by providing a disc-shapedrecording medium having formed thereon, according to the presentinvention, a spiral groove wobbled adaptively to a phase modulationsignal corresponding to address information composed of a sync signalincluding a plurality of sync unit patterns, address data and errorcorrection code for the address data.

These objects and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription of the best mode for carrying out the present invention whentaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the address recording apparatus accordingto the present invention.

FIG. 2 is a plan view of an optical disc having a spiral groove formedthereon.

FIG. 3 is a plan view showing how the grooves are wobbled.

FIG. 4 shows the configuration of address information (ADIP)corresponding to a write-read cluster RUB.

FIG. 5A shows a monotone bit, and FIG. 5B shows an ADIP bit.

FIG. 6 shows the configuration of an 8-bit sync part.

FIGS. 7A to 7D show four types of sync unit patterns included in thesync part.

FIG. 8 shows the configuration of a 75-bit data part.

FIGS. 9A and 9B show two different ADIP unit patterns.

FIG. 10 explains an error correction code for address data.

FIG. 11 shows a flow of operations made in recording an address in theaddress recording apparatus.

FIG. 12 is a block diagram of an optical disc drive for reproducingaddress information from an optical disc.

FIG. 13 shows a flow of operations made in recovery of addressinformation by a wobbling circuit.

FIGS. 14A to 14D explain together how address information is recovered.

FIG. 15 explains an example of FM modulation of address information.

FIG. 16 shows how the groove is wobbled correspondingly to a monotonebit and ADIP bit, respectively, when address information isFM-modulated.

BEST MODE FOR CARRYING OUT THE INVENTION

The address recording apparatus according to the present invention isconstructed as shown in FIG. 1. When an optical disc is being produced,there is formed on the optical disc 5 a groove G having a spiral formintended for tracking as shown in FIG. 2 and wobbled adaptively toaddress information as shown in FIG. 3.

As shown, the address recording apparatus according to the presentinvention includes an address generator 1. The address generator 1generates address information to be recorded to an optical disc 5 shownin FIG. 2. The address information is binary digital data composed of async signal, address data and an error correction code (ECC) for theaddress data. The address generator 1 converts the address informationinto a binary signal a(t) and supplies the signal to a modulator 3.Digital data “1” included in the address data is converted into a binarysignal a(t) (=1) while digital data “0” is converted into a binarysignal a(t) (=−1). It should be noted that the binary signal a(t)resulted from conversion of address information being binary digitaldata will also be referred to as “address information a(t)” hereunder.

The address recording apparatus includes also a carrier signal generator2 to generate a carrier signal x(t) (=cos θ(t)) which is to carry theaddress information, and supplies the signal to a modulator 3 alsoincluded in the apparatus.

The modulator 3 is provided to make phase modulation of the carriersignal x(t) by multiplying the address information a(t) supplied fromthe address generator 1 by the carrier signal x(t) (=cos θ(t)) suppliedfrom the carrier signal generator 2 and outputs, to a wobbling unit 4also included in the apparatus, a phase modulation signal y(t)(=a(t)·cos θ(t)) corresponding to resultant address information. Sincethe address information is a binary signal indicative of “1” or “−1” asmentioned above, the phase modulation signal y(t) is either in phasewith the carrier signal x(t), namely, y(t)=x(t)=cos θ(t) or in oppositephase to the carrier signal x(t), namely, y(t)=−x(t)=−cos θ(t).

The wobbling unit 4 forms, on the optical disc 5, a spiral groovewobbled according to the phase modulation signal y(t) supplied from themodulator 3.

The address recording apparatus further includes a controller 6 tocontrol a drive 7 to read a control program from a magnetic disc 8,optical disc 9, magneto-optical disc 10 or a semiconductor memory 11,and then control the entire address recording apparatus on the basis ofthe control program thus read.

FIG. 4 shows the configuration of address information recordedcorrespondingly to a write-read cluster RUB (read unit block) of theoptical disc 5. Two pieces of address information (ADIP: address inpre-groove) are recorded in the read-write cluster RUB. Each piece ofaddress information is of 83 bits of which 8 bits are for a sync part(SYNC) indicating a sync signal, and 75 bits are for a data partindicating address data and ECC for the address data.

Information of 1 bit is formed as 42 wobbles (for 42 cycles) on theoptical disc 5. One bit for the 42 wobbles is classified into a monotonebit for a succession of in-phase wobbles as shown in FIG. 5A, an ADIPbit, not any monotone bit, (a phase modulation takes in the period of 42wobbles) as shown in FIG. 5B, etc.

FIG. 6 shows the configuration of a sync part of 8 bits. As shown, thesync part is composed of four sync blocks “1” to “4” each including amonotone bit and a sync bit.

As shown in FIGS. 7A to 7D, a sync bit (for 42 wobbles) is composed of async unit for 12 wobbles and a monotone for 30 wobbles (succession ofin-phase wobbles).

FIGS. 7A to 7D show wobbles for sync blocks “1” to “4”, namely, a phasemodulation signal y(t). In FIGS. 7A to 7D and subsequent drawings anddescription, the upward arrow “↑” indicates a wobble for one cycle ofthe phase modulation signal y(t) (=cos θ(t)), and the downward arrow “↓”indicates a wobble for one cycle of a phase modulation signal inopposite phase to the carrier signal, that is, a phase modulation signaly(t) (=−cos θ(t)).

The sync unit (for 12 wobbles) in the sync block “1” is formed as afirst sync unit pattern “↓ ↓ ↑ ↑ ↓ ↓ ↑ ↑ ↑ ↑ ↑ ↑” as shown in FIG. 7A.The sync unit (for 12 wobbles) in the sync block “2” is formed as asecond sync unit pattern “↓ ↓ ↑ ↑ ↑ ↑ ↓ ↓ ↑ ↑ ↑ ↑” as shown in FIG. 7B.The sync unit (for 12 wobbles) in the sync block “3” is formed as athird sync unit pattern “↓ ↓ ↑ ↑ ↑ ↑ ↑ ↑ ↓ ↓ ↑ ↑” as shown in FIG. 7C.The sync unit (for 12 wobbles) in the sync block “4” is formed as afourth sync unit pattern “↓ ↓ ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↓ ↓” as shown in FIG. 7D.

The 8-bit sync part will include all the above-mentioned first to fourthsync unit patterns. For reproducing address information, when at leastone of the first to fourth sync unit patterns can be reproduced, theposition of the sync part, that is, the address information, canaccurately be determined.

FIG. 8 shows the configuration of the 75-bit data part. As will be seenfrom FIG. 8, the data part include fifteen ADIP blocks “1” to “15” eachcomposed of a monotone bit and four ADIP bits.

FIG. 9A shows a wobble corresponding to a monotone bit, that is, a phasemodulation signal y(t).

FIG. 9B shows a wobble corresponding to one of the four ADIP bitsincluded in one ADIP block, that is, a phase modulation signal y(t). AnADIP bit (for 42 wobbles) corresponding to 1-bit digital data “1” ofaddress data on the address information is composed of an ADIP unithaving a first ADIP unit pattern “↓ ↓ ↑ ↑” and a monotone for 38 wobblesnext to the ADIP unit. An ADIP bit (for 42 wobbles) corresponding todigital data “0” is composed of an ADIP unit having a second ADIP unitpattern “↑ ↑ ↓ ↓” and a monotone for 38 wobbles next to the ADIP unit.

FIG. 10 shows address data and an ECC for the address data. As shown, anECC (parity) of 32 bits (=8 nibbles) is added to address data of 28 bits(=7 nibbles). It should be noted that the 28-bit address data includes a20-bit RUB number, 2-bit RUB address number, 2-bit information for amultilayer disc and a four reserved bits. The error correction method isthe nibble-based Reed-Solomon Coding RS (15, 7, 9).

Referring now to FIG. 11, there is illustrates in the form of a flowchart operations made for recording of address information in theaddress recording apparatus according to the present invention. Theaddress recording will be described below with reference to FIG. 11.

In step S1 shown in FIG. 11, the address generator 1 generates addressinformation which is to be recorded to the optical disc 5 and composedof a sync signal, address data and an ECC for the address data, andconverts the address information into a binary signal a(t) and suppliesthe signal to the modulator 3. At the same time, the carrier signalgenerator 2 generates a carrier signal x(t) (=cos θ(t)) which is tocarry the address information, and supplies the signal to the modulator3.

In step S2, the modulator 3 generates a phase modulation signal y(t)(=a(t)·cos θ(t)) corresponding to resultant address information bymultiplying the address information a(t) supplied from the addressgenerator 1 by the carrier signal x(t) (=cos θ(t)) supplied from thecarrier signal generator 2 and supplies it to the wobbling unit 4.

Next in step S3, the wobbling unit 4 forms, on the optical disc 5, aspiral groove wobbled according to the phase modulation signal y(t)supplied from the modulator 3.

With the above address recording operations made by the addressrecording apparatus according to the present invention, addressinformation having four different sync unit patterns included in a syncsignal can be recorded as wobbles of the groove on the optical disc 5.

Referring now to FIG. 12, there is schematically illustrated in the formof a block diagram an example of the construction of the optical discdrive which writes and reads arbitrary data to and from the optical disc5 having address information written as wobbles of a groove thereon bythe address recording apparatus according to the present invention.

As shown in FIG. 12, the optical disc drive includes a control circuit21 which controls components of the optical disc drive according to acontrol program recorded in a recording medium 22. More specifically,the control circuit 21 controls the components of the optical disc driveaccording to a write command supplied from an external AV apparatus orthe like (not shown) via an AV interface 23 to write, to the opticaldisc 5, a mark corresponding to recording data supplied from the AVapparatus. Also, the control circuit 21 controls the optical disc drivecomponents to read a mark recorded in the optical disc 5 according to aread command supplied from the AV apparatus via the AV interface 23,reproduce the recorded data, and supply it to the AV apparatus via theAV interface 23.

The optical disc drive includes also a spindle circuit 24 to control therotation of a spindle motor 26 according to a command from the controlcircuit 21, and a servo circuit 25 to cause an optical pickup 27 to seekan address specified by the control circuit 21 and control the focusservo and tracking servo of the optical pickup 27 according to a focuserror signal and tracking error signal supplied from an optical headcircuit 28. The spindle motor 26 rotates the optical disc 5 under thecontrol of the spindle circuit 24.

The optical pickup 27 consists of a laser output system, return linedetecting system, biaxial actuator, etc. For data recording, the opticalpickup 27 is controlled by the optical head circuit 28 to radiate laserlight to the optical disc 5, thereby forming a mark on the optical disc5. For data reproduction, the optical pickup 27 radiate laser light ontothe optical disc 5, detects return light from the optical disc 5 andgenerate a corresponding return light signal, and supplies it to theoptical head circuit 28.

For data recording, the optical head circuit 28 controls the laseroutput from the optical pickup 27 correspondingly to a header signal orwrite-compensated signal supplied from the write-read circuit 29. Fordata reproduction, the optical head circuit 28 generates an RF signalcorresponding to an embossed pit and mark recorded on the optical disc 5on the basis of the return light signal from the optical pickup 27, andsupplies the RF signal to the write-read circuit 29. Further, for datareproduction, the optical head circuit 28 generates a focus error signaland tracking error signal on the basis of the return light signal fromthe optical pickup 27, and supplies it to the servo circuit 25 whichwill then generate a pushpull (will be referred to as “pp” hereunder)signal. The pp signal is supplied to a wobbling circuit 32.

For data recording, the write-read circuit 29 is controlled by thecontrol circuit 21 to make write compensation of a signal supplied froma modem circuit 30 and supply the compensated signal to the optical headcircuit 28. For data reproduction, the write-read circuit 29 convertsthe RF signal from the optical head circuit 28 into binarized data andsupplies the data to the modem circuit 30.

For data recording, the modem circuit 30 is controlled by the controlcircuit 21 to modulate ECC-added recording data supplied from an errorcorrection circuit 31 and supply the resultant signal to the write-readcircuit 29. For data reproduction, the modem circuit 30 demodulates thebinarized data supplied from the write-read circuit 29 and supplies theresultant read data to the error correction circuit 31.

For data recording, the error correction circuit 31 is controlled by thecontrol circuit 21 to add ECC to the recording data supplied from theexternal AV apparatus or the like via the AV interface 23, and suppliesthe data to the modem circuit 30. For data reproduction, the errorcorrection circuit 31 corrects any error of read data supplied from themodem circuit 30 on the basis of the ECC, and supplies the correcteddata to the external AV apparatus or the like via the AV interface 23.

The wobbling circuit 32 generates a wobbling signal (equal to the phasemodulation signal y(t)) corresponding to wobbles of a groove on thebasis of the pp signal supplied from the optical head circuit 28,recovers the address information a(t) from the wobbling signal y(t), andsupplies the recovered information to a address decoder/timing generator(DEC/TG) 33.

The DEC/TG 33 detects the position of a sync part by detecting at leastone of the four types of sync unit patterns included in the sync partfrom the address information a(t) supplied from the wobbling circuit 32,generates an address based on address data and ECC for the address dataincluded in a data part next to the sync unit, and supplies the addressto the control circuit 21. Also, the DEC/TG 33 generates a timing signalon the basis of the detected sync part, and supplies the timing signalto various circuits in the optical disc drive via the control circuit21.

Next, how the wobbling circuit 32 recovers address information from awobbling signal will be described with reference to the flow chart shownin FIG. 13. The address information recovery is effected for recordingarbitrary data to the optical disc 5 and also for reproducing datarecorded in the optical disc 5.

In step S11, the wobbling circuit 32 generates a wobbling signalcorresponding to wobbles of a groove on the basis of the pp signalsupplied from the optical head circuit 28, namely, a phase modulationsignal y(t) as shown in FIG. 14A.

In step S12, the wobbling circuit 32 extracts a carrier signal x(t)(=cos θ(t)) as shown in FIG. 14B from the phase modulation signal y(t)(=a(t)·cos θ(t)), and multiplies the phase modulation signal y(t) by thecarrier signal x(t) to generate a signal z(t).z(t)=a(t)·cos 2θ(t)=a(t)·(cos 2θ(t)+1)/2

In step S13, the wobbling circuit 32 removes a high-frequency noisecomponent from the signal z(t) by means of an incorporated lowpassfilter. In step S14, the wobbling circuit 32 binarizes the signal z(t)from which the noise component has been removed to recover addressinformation a(t) as shown in FIG. 14D. With the above operations, thewobbling circuit 32 recovers the address information.

As having been described in the foregoing, the optical disc driveaccording to the present invention can detect the position of a syncpart by detecting at least one of the four types of sync unit patternsincluded in the sync part. Thus, it is possible to acquire address dataand ECC for the address data included in a data part next to the syncpart and generate an address from the address data and ECC. So, it ispossible to improve the address error rate for reproduction of data andaccurately access a given address on the optical disc 5.

In the aforementioned modulator 3 of the address recording apparatus,address information a(t) is subjected to phase modulation and a groovewobbled adaptively to a resultant phase modulation signal is formed onthe optical disc 5. However, it should be noted that address informationa(t) may be subjected to FM modulation (frequency modulation) and agroove wobbled adaptively to a resultant FM modulation signal may beformed on the optical disc 5.

More particularly, in case the address information a(t) is “1” as shownin FIG. 15 for example, there is generated an FM modulation signalhaving the same frequency as that of a carrier signal and in phase withthe latter. When the address information a(t) is “0”, there is an FMmodulation signal whose frequency is a half of that of the carriersignal and which is in phase with the latter.

Even in case the FM modulation is used, 1-bit information is classifiedinto a monotone bit for a succession of 42 wobbles whose frequency isthe same as that of a carrier signal and which is in phase with thelatter, and an ADIP bit or the like which is not any monotone bit and inwhich an FM modulation takes place in a period of 42 wobbles in carrierfrequency units, as shown in FIG. 16.

In the optical disc drive to read the optical disc 5 having formedthereon a groove wobbled adaptively to the FM modulation signal ofaddress information a(t), a wobbling signal to be read is FM demodulatedto recover the address information.

Note that the present invention may be applied for recording andreproducing address information to and from the optical disc 5 as wellas from disc-shaped recording media of all types.

The aforementioned series of operations can be carried out by ahardware, and also by a software. In the latter case, a program formingthe software is installed from a recording medium in a computer havingdedicated hardware for execution of the program or in a general-purposepersonal computer, for example, which can execute various functions byinstalling a variety of programs.

As shown in FIG. 1, the recording medium is not only a package mediumsuch as a magnetic disc 8 (including a floppy disc), optical disc 9(CD-ROM (=compact disc-read-only memory), DVD (digital versatile disc),magneto-optical disc 10 (including mini disc (MD)) or a semiconductormemory 11, distributed to the users for serving the program and havingthe program recorded therein, but a ROM or hard disc built in a computerin advance and having the program recorded therein.

Note that in the present invention, the steps of describing the programto be recorded in a recording medium include, of course, operations madetime-serially in the described order of them, and also operations madenot time-serially but in parallel or individually.

INDUSTRIAL APPLICABILITY

As having been described in the foregoing, the address informationrecording apparatus and method and the first program according to thepresent invention are such that there is formed on a disc-shapedrecording medium a groove wobbled adaptively to a phase modulationsignal corresponding to address information composed of a sync signalincluding a plurality of sync unit patterns, address data and an errorcorrection code of the address data. Thus, it is possible to record, tothe disc-shaped recording medium, address information permittingaccurate detection of the position of the sync signal.

Also, the address information reproducing apparatus and method and thesecond program according to the present invention are such that awobbling signal is demodulated to recover address information composedof a sync signal including a plurality of sync unit patterns, addressdata and an error correction code of the address data, at least one of aplurality of sync unit patterns including in the sync signal in theaddress information is detected, the address data and error correctioncode for the address data is extracted from the address information onthe basis of the position of the detected sync unit pattern, and theaddress data and error correction code are used to reproduce an address.Thus, it is possible to access a given address quickly and accurately.

Since the disc-shaped recording medium according to the presentinvention has formed thereon a spiral groove wobbled adaptively to aphase modulation signal correspondingly to address information composedof a sync signal including a plurality of sync unit patterns, addressdata and an error correction code of the address data, it is possible toaccess a given address quickly and accurately.

1. An apparatus for reproducing an address on a disc-shaped recordingmedium on the basis of wobbles of a groove formed on the disc-shapedrecording medium, the apparatus comprising: radiating means forradiating laser light to the disc-shaped recording medium; return lightdetecting means for detecting return light from the disc-shapedrecording medium to generate a return light signal corresponding to thereturn light thus detected; wobbling signal generating means forgenerating a wobbling signal corresponding to the wobbles of the grooveon the basis of the return light signal generated by the return lightdetecting means; demodulating means for demodulating the wobbling signalgenerated by the wobbling signal generating means to recover addressinformation composed of a sync signal including a plurality of sync unitpatterns, address data and an error correction code for the addressdata; means for detecting at least one of the plurality of sync unitpatterns included in the sync signal in the address informationrecovered by the address information recovering means, each sync signalincluding two first signals of a first phase, and a second signal of asecond phase opposite the first phase, the second signal formed betweenthe two first signals to separate the two first signals; sync unitpattern detecting means for acquiring the address data and the errorcorrection code for the address data from the address information on thebasis of the interval between the two first signals separated by thesecond signal of the sync unit pattern detected by the sync unit patterndetecting means; and reproducing means for reproducing the address onthe basis of the address data and the error correction code for theaddress data, extracted by the acquiring means.
 2. The apparatus as setforth in claim 1, wherein the disc-shaped recording medium is an opticaldisc.
 3. The apparatus as set forth in claim 1, further comprising meansfor generating a clock signal on the basis of the position of the syncunit pattern detected by the detecting means.
 4. A method for use in anapparatus for reproducing an address on a disc-shaped recording mediumon the basis of wobbles of a groove formed on the disc-shaped recordingmedium, the method comprising: radiating laser light to the disc-shapedrecording medium; detecting return light from the disc-shaped recordingmedium to generate a return light signal corresponding to the returnlight thus detected; generating a wobbling signal corresponding to thewobbles of the groove on the basis of the return light signal generatedin the return light detecting; demodulating the wobbling signalgenerated in the wobbling signal generating to recover addressinformation composed of a sync signal including a plurality of sync unitpatterns, address data and an error correction code for the addressdata, each sync signal including two first signals of a first phase, anda second signal of a second phase opposite the first phase, the secondsignal formed between the two first signals to separate the two firstsignals; detecting at least one of the plurality of sync unit patternsincluded in the sync signal in the address information recovered in theaddress information recovering; acquiring the address data and errorcorrection code for the address data from the address information on thebasis of the interval between the two first signals separated by thesecond signal of the sync unit pattern detected in the sync unit patterndetecting; and reproducing the address on the basis of the address dataand the error correction code for the address data, extracted in theacquiring.